The invention generally relates to wind turbines and, more particularly, to a system for actuating wind turbine blades in the wind turbine.
Conventional wind turbine blades are controlled using various methods to enhance the structural and aerodynamic performance of the wind turbine blades. One such method may include pitch control of complete wind turbine blade to reduce structural loads and aerodynamic loads at a root of the wind turbine blade. However, the aforementioned method is limited to performing pitch control for the complete wind turbine blade and is unable to perform one or more functions associated with reducing the structural loads and the aerodynamic loads of the wind turbine blade such as local morphing of the shape of the wind turbine blade, flapping of trailing edge, and activating synthetic jets. The one or more functions help in reducing the structural loads and the aerodynamic loads in the wind turbine blade, which increases the efficiency of the wind turbine. However, conventional actuation mechanisms such as electrical drives, hydraulic, and pneumatic drives may not be feasible to perform the one or more functions of the wind turbine blades as the conventional actuation mechanisms are generally heavy and require additional power supply accessories which may create undesirable complexities and mass/weight penalties on the wind turbine.
Previous system and method for actuating wind turbine blades have included actuation mechanisms utilizing shape memory alloys (SMAs). Due to their high power density, reliability/availability (lack of moving parts, corrosion resistance, electrical activation, etc.), shape memory alloys (SMAs) are nearly ideal actuators for such control tasks. Such use of an SMA actuator mechanism is discussed in commonly assigned, pending PCT Application Ser. No. PCT/US15/25839, Buravalla, V. et al., “SYSTEM FOR WIND TURBINE BLADE ACTUATION”. Said application includes the use of an SMA torque tube to change the tip incidence between two states, when having different torsion angles below and above the shape change temperature. In many instances, costs of such an SMA tubes and the time to thermally activate it would be very high.
Accordingly, there is a need for an improved system and method for actuating the wind turbine blades.